Hey Josefina,

That sounds a bit weird, I'd suggest to uninstall all the Zotero plugins and reinstall them. You also don't need to do "On change", for a start I'd output the bibtex file to desktop and try to load it from there and see if your problem persists.

Let me know how it goes, I hope you can at first manage to load in your citations in obsidian, once we figure out that step we can debug zotero.